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Superfamily
Acid Protease
(as classified by SCOP) |
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Viral
HIV-1 Protease (PR)
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Mammalian
Renin
|
| Comparison
of PR with microbial and mammalian aspartyl proteases reveals considerable
structural homology and similarities as demonstrated with pepsin-like
proteins such as renin, chymosin, and penicillopepsin. Aspartyl Proteases are mostly found in acidic environments (renin is an exeption). Activity of the aspartyl proteases is inhibited by pepstatin A and by a mutation of the Asp in the active site triad. In PR, the residue following the catalytic triad is Ala28, characteristic of retroviral proteases. In bacterial or mammalian proteases, Ser or Thr usually follow the triad. |
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Viral
HIV-1 Protease (PR)
|
Mammalian
Renin
|
| PR is a dimer, unlike most other proteases in the Aspartyl Protease Family (monomers). It contains fewer amino acid residues than bacterial or mammalian proteases and is the smallest of all retroviral proteases. |
 |
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|
Viral
HIV-1 Protease (PR)
|
Mammalian
Renin
|
| The b-sheet that contibutes the catalytic triad is made up of four short strands in PR, rather than six long strands as in in bacterial or mammalian proteases. The monomeric proteases contain only one flap, a beta hairpin loop which folds over the substrate; PR has two. |